The present application relates to a method of fabricating a memory device embedded in a back-end-of-the-line (BEOL) structure for use in a neuromorphic computing system. More particularly, a conformal disposable absorber is disclosed which is capable of providing efficient heat transfer to an embedded memory device during a localized absorber anneal, without adversary impacting the BEOL structure.
Neuromorphic computing systems, also referred to as artificial neural networks, are computational systems that permit electronic systems to essentially function in a manner analogous to that of biological brains. Neuromorphic computing systems do not generally utilize a traditional digital model of manipulating Os and is. Instead, neuromorphic computing systems create connections between processing elements that are roughly functionally equivalent to neurons of a biological brain.
Neuromorphic computing systems may include memory devices that are embedded in a back-end-of-the-line (BEOL) structure. Examples of memory devices that can be employed in neuromorphic computing systems and embedded in a BEOL structure may include ferroelectric (FE) memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), and/or phase change random access memory (PRAM).
In the fabrication of memory devices that are embedded in a back-end-of-the-line (BEOL) structure, a high temperature thermal anneal such as, a flash anneal or rapid thermal anneal, may be useful in order to optimize one or more elements of the embedded memory device. For example, FE memory devices including a stack of TiN/HfO2/TiN require a high temperature rapid thermal anneal budget (greater than 600° C./1 second) to enable HfO2 to recrystallize to exhibit a ferroelectric capacitance behavior. The high thermal anneal budget requirement is incompatible with the elements of the BEOL structure.
In addition to using thermal anneals, a high temperature (about 1000° C.) nanosecond laser anneal, which has a much less thermal budget than rapid thermal annealing, has been used to provide HfO2 with ferroelectric capacitance behavior. However, and given that the BEOL dielectric material is optically transparent to laser illumination, the direct illumination of the laser to the BEOL structure will create undesirable heating effects of the electrically conductive metal or metal alloy structure embedded in the interconnect dielectric material of the BEOL structure.
There is thus a need for providing a method which can be used to fabricate an embedded memory device in a BEOL structure that substantially, or even entirely, eliminates the aforementioned problems associated with annealing of such memory devices.